GLTF files in three js
That last link (to the official blender addon docs) is the right workflow, if you already know the basics of creating materials in Blender. If not, I would start with a tutorial on Blender's Principled BSDF, like this one. If you follow the guidelines in the addon docs, a Principled BSDF material will export to glTF correctly.
More information in https://discourse.threejs.org/t/dont-know-how-to-create-gltf-file-suitable-for-three-js-in-blender/13065.